This invention relates to an electronic drum for transducing vibration, which is produced through the striking of the drum by a striking member, such as a drumstick, to an electric signal and electrically generating a predetermined musical tone corresponding to the electric signal, and in particular to an electronic drum which can positively and exactly detect vibration as produced through the striking of the drum by a striking member, such as a drumstick, so that the performer can enjoy an excellent beating "feel" on the drum.
As one of the conventional percussion instrument an electronic drum has been developed which picks up vibration produced through the striking of the drum by the drumstick as a corresponding electric signal and electrically generates a drum sound based on the picked-up electric signal. In this type of electronic drum it is important that only the vibration resulting from the beating of the drum by the drumstick be positively and exactly picked up to generate a drum sound of a level exactly in proportion to the intensity of a beat impact by the striking member, such as a drumstick, so that the performer can enjoy an excellent percussion "touch" or "feel" during performance without being considerably fatigued even when a performance is made over a longer period of time.
In this connection, U.S. Pat. Nos. 4,581,972 and 4,581,973 disclose an electronic drum in which a cushioning member and vibration plate are arranged, as a layer structure, within a shallow-bowl type drum shell in that order as viewed from the inner bottom of the drum shell toward a batter head with a sensor attached to the vibration plate. In this electronic drum, a ring-like cushioning member is attached to the outer periphery of the vibration plate and a lower annular cushioning member is attached to the outer marginal edge portion of the vibration plate. These cushioning members prevent the generation of a vibration noise resulting from the contact of the vibration plate per se with the drum shell during performance, as well as presents the transmission, to the vibration plate, of percussion noises which result from the inadvertent beating of other than the batter head by the stick. The cushioning member mounted on the vibration plate damps an external strike force on the batter head during performance, so that the performer can experience an improved "feel" or "touch" during performance.
In the aforementioned conventional electronic drum, however, the lower cushioning member as a whole is made of a uniform elastic material of a predetermined elastic property. The lower cushioning member is placed directly on the inner bottom surface of a shallow-bowl type drum shell or on a support fixed to the drum shell and, if the lower cushioning member is not exactly so formed as to have a uniform thickness, a clearance is left between a drumhead member mounted on the marginal edge portion of an upper opening of the drum shell and the cushioning member placed over the lower cushioning member with the vibration plate therebetween. As a result, it is not possible to place the aforementioned associated members as an intimately layered unit. Upon the beating of the drumhead by the striking member, such as a drumstick, under this situation, a discordant sound is generated due to a collision between the vibration plate and the cushioning member and between the vibration plate and the drumhead member. The cushioning member and lower cushioning member with the vibration plate mounted therebetween can damp a relatively light strike force acting on the drumhead member, to the extent that the performer can enjoy a better percussion "touch" without causing any beating reaction in the performer during performance. When, on the other hand, a beating force exceeding a predetermined magnitude is continuously applied to the drumhead member, the aforementioned members cannot be adequately so damped that the performer may enjoy the performance to that aforementioned extent. Since the aforementioned predetermined magnitude is lower than that on the traditional acoustic drum, the performer is more readily liable to get tired when the drum is beaten by a relatively great strike force over a relatively longer period of time.